Liquid level control system



Dec. 17, 1940- E, E, HOLLANDER 2,225,498

LIQUID LEVEL CONTROL SYSTEM Filed April 30, 1938 i i I a INVENTOR.

Elvin E. Hollander Patented Dec. 17, 1940 "UNITED STATES PATENT OFFICE LIQUID LEVEL CONTROL SYSTEM Elvin E. Hollander, Bloomfield, N. J., assignor to Star Equipment Corporation, Bloomfield, N. J a corporation of New Jersey Application April 30, 1938, Serial N 0. 205,278

2 Claims.

or other liquid, in a tanker some form of recap-- tacle, be kept as fresh as possible and the level be 10 kept substantially at a given level although at the time a fresh supply of the liquid is being fed to the receptacle at a rate which might vary over a substantial range. Many different forms of devices or systems for meeting this requirement have been proposed heretofore, but each of these has one or more disadvantages in the way of being more or less complicated, embodying movable parts which fail to function properly after long usage, and being effective to keep the liquid fresh in only a relatively small section of the receptacle. For example, in some forms of drycleaning machines of the general type disclosed in the pending applications Serial Nos. 25,076 and 140,856, filed June 5, 1935, and May 5, 1937, respectively, and in which a basket containing the garments to be cleaned is oscillated in a tank containing the cleaning solvent, fresh cleaning solvent is supplied constantly to the tank during the washing or cleaning operation, and the desired 30 level maintained by the solvent spilling over a wall or flowing out through a riser whose upper end or edge is at the desired level. In such an arrangement, the liquid in the tank is maintained at the desired level, but the important require- 35 ment of keeping the liquid as fresh as possible throughout the tank is not satisfied. The reason for this is that discharge of the liquid from the tank takes place at only one level therein, that is, at the top level at which the liquid is maintained. 40 The oscillation or other movement of the basket in the tank naturally stirs up or agitates the liquid in the tank so that some of the solvent at the bottom circulates to the top and is discharged, but in spite of this action, the freshness of the 45 solvent throughout the tank is not as uniform as it might be.

With the foregoing in mind, it is one of the objects of my invention to provide an improved system of the character referred to in which the 5 level of the liquid in a receptacle is maintained substantially at a given level although it is being constantly supplied with fresh liquid at a rate which might vary over a substantial range, and in which the freshness of the liquid throughout the receptacle is maintained substantially more uni- 5 form than has been the case in the various systems and methods proposed heretofore.

Other objects and advantages will hereinafter appear.

For the purpose of illustrating my invention,

an embodiment thereof is shown in the drawing,

in which Figure 1 is a simplified, elevational view, partly in section, of a liquid-level control system constructed and operating in accordance with my invention;

Figure 2 is an enlarged, fragmentary view taken from Figure 1, illustrative of the operating principle; and

Figure 3 is a view similar to Figure 1, showing a modification.

The reference numeral l0 designates a tank or other receptacle for liquid. Means providing an inverted U sh'ape syphonic liquid-discharge passage from the tank comprises a relatively short leg 'I l communicating at its lower end l2 with the tank at the bottom thereof, and a relatively long leg [3 having its lower end I'4 disposed below the lower end I2 of the short leg to make possible the syphonic action.

A passage I 5 operates to vent the Syphon from the interior of the tank at the level Hi at which it is desired the liquid be substantially maintained. The vent passage I5 is disposed to provide, with the long leg l3 of the syphom'c liquiddischarge passage, an overflow-discharge from the tank at the level I6.

The long leg 13 of the syphon discharges into suit-able treating apparatus represented at IT, and in which the liquid may be filtered, chemically 40 treated, or otherwise acted upon as might be re-. quired in any particular case, to restore the liquid substantially to the original condition it was in beforehaving been fed to the tank [0.

The liquid is drawn from the apparatus I bya suitable pump I8, and discharged into the tank ID, as shown.

In explaining the principle of operation, it will be assumed that the level of the liquid in tank I0 is momentarily at 16a, as represented in Figure 2.

The condition which then exists may be expressed as follows:

wherein Q13 is the rate of fluid-flow or discharge through the leg l3;

Q11 is the rate of liquid discharge upward through the leg I I and over into the leg 13 due to the syphonic action, as represented by the arrows l9;

Q15 is the rate of overflow-discharge of the liquid from the tank through the vent passage l5 into the leg 13, as represented by the arrows 2E and Qa is the rate at which air is drawn or sucked into the Vent passage i5 from the interior of the tank, between the edge 21 of the vent opening and the surface of the liquid at the level 16a, as represented by the arrow 22. M If the rate of liquid discharge from the supply pipe 23, designated as Qs, at the time equals Q11+Q15, the level obviously will remain at its.

If Qs at the time is less than Qll-l-Qlfi, the' level IBa will drop to admit more air into the vent passage l5 and increase Qa and correspondingly decrease Q11+Q15 until the latter equals Qs, at which time the liquidlevel will remain constant.

If Qs at the time is greater than Q11+Ql5, the level Eta will rise to admit less air into the vent passage l5 and accordingly decrease Qa and increase Ql1+Q15 until the latter equals Qs, at which time the liquid level will remain constant.

From the foregoing it will be seen that in my improved system, occurring variation of Qs, even over a substantial range, is automatically compensated for by the self-adjustment of the airvent opening, whereby the level of the liquid is maintained at about the level 16.

Since there is withdrawal or dischargeof the liquid simultaneously from the, top and bottom of the tank in my improved system, the fresh ness of the liquid throughout the tank, is more uniform than would otherwise be the case.

In some cases it might be desirable to cause discharge of liquid from tank lfl at ,a greater rate from one level than from another. level, in which case the relation of the respectiveareas of the two discharge openings irom the tank would be made to suit the particular condition or requirement. For example, in an aquarium it might be more effective to discharge more water from the bottom of the tank, particularly if the inflow'of fresh water is at the top. In such case, the diameter of the leg ll would be made greater than that of the vent passage I5.

In a practical embodiment of my invention, satisfactory results were obtained using a diameter oi /2 inch for the vent passage l5 and a diameter of 1 /2 inches for each of the legs H and I3.

In my improved system, the vent passage I5 is disposed to be submerged at the desired level It. Also, it is important in my improved system that the lower limit 9 of the crown portion of the syphonic passage be disposed as shown to efiect the syphonic action at the desired level l6, continuously and simultaneously with the overflow-discharge QI5.

For the purpose of providing for an adjustment of the level maintained in the tank It, an

arrangement such as is shown in Figure 3 might be used. In this case, there are the three vent passages 15a, l5b and I50 controlled by the valves 24, 25 and 26, respectively, and each corresponding to and serving the same purpose as the vent passage l5 in Figures 1 and 2. It will be seen that with valves 24 and 25 closed and valve 25 open, as shown, the liquid level will be maintained at substantially 21, that with valves 24 and 25 closed and valve 26 open, the liquid level will be maintained at substantially 28, and that with valves 25 and 26 closed and valve 24 open, the liquid level will be maintained at substantially 29. The principle of operation is the same as in Figures 1 and 2.

It will be understood that in any embodiment of my invention, the discharge from the leg I3 may go to waste, and the supply to the pump it taken from an independent source.

It will be understood that various modifications, other than those shown, are possible with out departing from the spirit of my invention or the scope of the claims.

I claim as my invention:

1. In a liquid-level control system, a receptacle for liquid, and means providing an inverted U-shape syphonic liquid-discharge passage comprising a relatively short leg communicating at its lower end with said receptacle and a relatively long leg having its lower end disposed below the lower end of said short leg to make possible the syphonic action, said system being provided with a passage for venting the syphon from the interior of said receptacle at the level therein at which it is desired the liquid be substantially maintained, said vent passage being disposed to be substantially entirely submerged at said level and to provide with said long leg of the syphonic liquid-discharge passage an overflow-discharge from said receptacle at said level, the lower limit of the crown portion of said syphonic passage being disposed substantially below said level and said crown portion of said syphonic passage being disposed to eiiect the syphonic action at said level continuously and simultaneously withsaid overflow-discharge, the inlet side of said vent passage having a dimension in the vertical direction and being disposed to permit an overflow-discharge by way of said vent passage and said syphonic liquid-discharge passage under conditions of liquid-level below the upper edge of said vent passage.

2. In a liquid-level control system, a receptacle for liquid, and adjustable means for syphoning oh? the liquid from said receptacle at selected levels; said means including means providing an inverted U-shape syphonic liquid-discharge passage comprising a relatively short leg communicating at its lower end with said receptacle and a relatively long leg having its lower end disposed below the lower end of said short leg to make possible the syphonic action, and a passage for venting the syphon from the interior of said receptacle at the level selected and disposed to provide with the long leg of the syphon an overflow-discharge from said receptacle at the level selected.

ELVIN E. HOLLANDER. 

